Prince William Sound was a Piedmont glacier which covered all of the area during the Pleistoscene ice ages. This glacial area retreated drastically about 12,000 years ago. The retreat created many deep fjords, islands, and numerous freshwater streams feeding rich estuaries. Through the thousands of years, ocean currents brought large amounts of plankton. The plankton brought marine animals forming the new habitat. The Humpback and Minke whales might of been the first whale to come to the Sound. Once the food supply increased, new mammals arrived into the Sound such as sea otters, harbor seals, Stellar sea lions, and killer whales.

On March 24, 1989, The Exxon Valdez oil tanker struck the Bligh Reef in Prince William Sound. The tanker spilled 11 million gallons of oil into Prince William Sound. The oil reached nearly 600 miles southwest from Bligh Reef. The oil moved along the coastline of Alaska moving to the shoreline of Prince William Sound, Kenai Peninsula, lower Cook Inlet, Kodiak Archipelago, and the Alaska Peninsula. The cleanup cost around 2.1 billion dollars. The oil effected many marine animals and oil can still be found in the Sound today.